1. Field of the Invention
The present invention relates to a photomask inspection method, a semiconductor device inspection method, and a pattern inspection apparatus which inspect a pattern of an inspection object in which a plurality of mutually replaceable unit regions are set.
2. Background Art
Conventionally, the existence or absence of defects in a semiconductor device including fine structures is inspected by capturing an optical image of the semiconductor device and comparing the optical image to reference data created based on design data and the like. Similar methods are used to inspect the existence or absence of defects also for photomasks used to manufacture such a semiconductor device (for example, refer to JP-A 2000-47369 (Kokai)).
However, in recent years, large scales and high integration have advanced for semiconductor devices experiencing rapidly growing demand such as nonvolatile semiconductor memory and LSIs with embedded memory. Attempting to manufacture a semiconductor device without any defects would result in undesirably low yields. Large scales and high integration have advanced similarly for photomasks used to manufacture such semiconductor devices. Attempting to manufacture a photomask without any defects also would result in undesirably low yields.
Redundancy technology is therefore applied to semiconductor devices and photomasks. Redundancy technology is a technology that remedies the semiconductor device or the photomask by making unit regions for redundancy beforehand in addition to the originally necessary unit regions such that a unit region in which a defect has occurred can be replaced with a redundant normal unit region. Thereby, the entire semiconductor device or photomask is prevented from being defective due to a small number of defects, and yields can be improved. In the case where the semiconductor device is, for example, a nonvolatile semiconductor memory, the unit region is, for example, a memory cell. The number of remediable unit regions for the semiconductor device and the photomask is determined by the number of unit regions made beforehand for redundancy.
However, in recent years, large scales and high integration are advancing even further for semiconductor devices and photomasks while the number of remediable unit regions is limited. Therefore, it remains difficult to manufacture semiconductor devices and photomasks with high yield even when using redundancy technology.